1. Field of the Invention
The present invention relates generally to the field of esophageal speech, and more particularly, to a method for enhancing the clarity of esophageal speech.
2. Description of Related Art
Persons who have had laryngectomies (that is, a surgical removal of the larnyx, most often for treatment of laryngeal cancer) have several options for the restoration of speech, none of which have proven to be completely satisfactory. One relatively successful method, esophageal speech, requires speakers to insufflate, or inject air into the esophagus, thereby replacing the vibration that is normally created by the vocal cords within the larynx, with the vibration of the esophagus. This method is discussed in the article "Similarities Between Glossopharyngeal Breathing And Injection Methods of Air Intake for Esophageal Speech," Weinberg, B. & Bosna, J. F., J. Speech Hear Disord, 35:25-32, 1970, herein incorporated by reference. Esophageal speech is frequently accompanied by an undesired audible injection noise, sometimes referred to as an "injection gulp" or "clunk" which sounds similar to a belch. Not only is this sound unpleasant, but the undesirable effect of the injection gulp is magnified because esophageal speakers generally have low vocal intensity. In addition, for some speakers the injection noise can be mistaken for a speech segment which further diminshes the intelligibility of the speakers voice. A further discussion of these effects may be found in the article "A Comparative Acoustic Study of Normal, Esophageal, and Tracheoespphageal Speech Production, " Robbins, J., Fisher, H. B., Blom, E. C., and Singer, M. I., J. Speech Hear Res, 49:202-210, 1984, herein incorporated by reference.
Considerable work has been undertaken to enhance certain aspects of esophageal speech. Examples of these techniques are discussed in "Replacing Tracheoesophageal Voicing Sources Using LPC Synthesis, " Qi, Y., J. Acoust. Soc. Am., 88:1228-1235, and in "Enhancement of Female Esophageal and Tracheoesophageal Speech," Qi, Y., Weinberg, B. and Bi, N., J. Acoust. Soc. Am., 98:2461-2465, both herein incorporated by reference. Although considerable work has been done in improving esophageal speech, the problem of eliminating injection noise has not been successfully addressed. In addition, there is no device that both eliminates the injection noise, and enhances the voice quality of esphageal speakers.